Buried 100ft below the ground in a disused London Underground air raid shelter, the last thing you would expect to find is micro-herbs and miniature vegetables being grown on an industrial scale.

But two entrepreneurs have managed to transform the former World War Two tunnels that sit 33 metres under Clapham North tube station into a 2.5-acre underground food garden, maintained via special low-energy LED bulbs.

Growing Underground, masterminded by Richard Ballard and Steven Dring, may sound like a publicity stunt, but with the cost of rental just over £1 per square foot, you'd be hard pressed to find a cheaper growing space elsewhere in the capital. They believe it will be a profitable and sustainable business and have got the backing of celebrity chef Michel Roux.

Built during the war, the idea behind the tunnels was to create a deep air raid shelter that could then be used to create an extra run of the Northern Line at a later date. The tunnels once held more than 12,000 people during a raid in 1944, but due to a lack of funds the tube was never extended and they have since sat empty.

And while dank tunnels might not be to everyone's taste, the natural temperature inside the cavernous spaces - 16 degrees celsius - is perfect for growing a range of delicacies.

Micro-herbs are also high-value produce - according to Steven, each square meter patch will generate on average around £1,200 per year.

The concept has gone down well with investors - the group is currently crowdfunding for investment via crowdcube to plough money into the business and further develop the space, which is rented from Transport for London.

They are asking investors to buy a stake in Growing Underground from as little as £10, while putting in £25,000 will buy voting rights.

Unusually for an agricultural project, it has managed to attain EIS and SEIS approval, meaning that investors will benefit from tax relief.

Having nearly doubled their original £300,000 funding target, the pair now hope to hit the £1million mark. Once the farm is fully up and running, they plan to employ 15 members of staff.

Growing Underground has also joined forces with acclaimed celebrity chef Michel Roux Jr, who joined the company as a director, and will use his Michelin-star experience to advise on taste and crop selection.

The business will focus on selling to wholesalers at first, until production is more established, but greens are likely to be sold to restaurants and supermarkets further down the line. Wholefoods has already been in contact about a possible partnership.

The tunnels will be carbon neutral, with energy sourced from green suppliers. Food miles will also be kept to a minimum, thanks to the central London location.

GROWING UNDERGROUND: 60 SECONDS WITH MICHEL ROUX

Richard and Steve’s PR advisor sent me an irresistible teaser about the project and we met at Le Gavroche. By the time I’d heard the opening sentence of their pitch I was totally hooked. We got on like a house on fire from the start. It’s such an interesting and clever idea that I just couldn’t say no.

What do you think about the idea of a farm underground?

The site is amazing and really atmospheric. I live in Clapham, so the tunnels are right beneath my doorstep. I knew the tunnels were there but I’d never visited.

Richard and Steve, the founders, are absolutely passionate about food. I was inspired by the their knowledge, their passion and by the huge amount of research they’d done. They’ve thought of everything.

I also like their ethos. They’re crowdfunding, so there’s an opportunity for investors who are passionate about food to get involved.

Does the produce taste any different to the same produce grown in the traditional way?

I am really impressed with the taste of the produce they’re growing. The flavours are vibrant and lively. It couldn’t be fresher.

There’s so much that can be grown – from exotic herbs to micro vegetables - and I will responsible for advising on produce selection and on markets. The produce will be right at home in high end restaurants and we’re sure that there will be lots of interest from wholesalers and retailers when we start trading.

What is your take on the environmental impact of the farm?

We’re determined to make the farm zero carbon.

All energy will be sourced from green providers, the lighting uses very low wattage, there are no heating bills and there are various options under consideration that will bring the footprint down to zero.

No heavy machines, such as tractors, are used in the way that they would be on a conventional farm. One other major advantage is the massive reduction in food miles and the freshness of the produce.